Mineral oil composition



MINERAL on. COMPOSITION No Drawing. Application June 27, 1952, Serial No. 296,061

8 Claims. (Cl. 252-46.7)

The present invention relates to the improvement of hydrocarbon oil products derived from petroleum sources and more particularly to the preparation of improved mineral lubricating oil compositions by the incorporation therein of a class of additives which imparts improved properties to such compositions.

In the development of petroleum base lubricating oils, the trend has been to use more and more efficient refining methods in order to reduce the tendency of the oils to form carbon and deposits of solid matter or sludge. While such highly refined oils possess many advantages, their resistance to oxidation particularly under conditions of severe service is generally descreased as a result of the refining and they are more prone to form oil soluble acidic oxidation products which are corrosive. They are also generally less eifective than the untreated oils in protecting the metal surfaces which they contact against rusting-and corrosion dueto oxygen and moisture.-

In accordance with the present invention a new class of compounds has been discovered which, when added to refined lubricating oils and other petroleum hydrocarbon oil products in small proportions, substantially reduce the tendency of such oils to corrode the metal surfaces, particularly the surfaces of copper-lead and cadmium-silver bearings which are employed in internal combustion engines, and they are likewise effective in inhibiting oxidation of hydrocarbon products generally.

The new class of materials which have been found to possess the antioxidant and stabilizing properties described above have the following general formula:

in which the R and R1 groups represent hydrocarbon radicals each having in the range of 1 to 30 carbon atoms, preferably 1 to carbon atoms. These hydrocarbon radicals may be open chain aliphatic radicals, which may .belong or short, straight or branched, saturated or un- In the above formulas M represents a salt-forming atom or group, and X represents a halogen atom. The

reaction is readily carried out by suspending a salt, e. g., a metal, ammonium or amine salt, of the thio acidof phosphorus in an inert medium such as petroleum ether or benzene, in which the reaction product is substantially completely soluble and in which the metallic halide byproduct is substantially insoluble, and mixing therewith or adding the thiocarbamyl halide followed by refluxing and stirring. The reaction will proceed at substantially room temperature, but it is preferable to heat the mixture slightly, such as at reflux temperatures, in order to accelerate the reaction. The halide salt which separates from the liquid medium is then filtered oil, and the solvent is removed by heating on a steam bath or under reduced pressure.

Specific compounds useful for the purposes of the present invention may be prepared by starting with materials having organic groups of a character falling within the scope of the compounds described above. For example, in preparing the organo-substituted thio acids of phosphorus, a large variety of alcohols and phenols may be employed as the original starting materials. Illustrative of such materials are the monohydric aliphatic alcohols such as ethyl alcohol, isopropyl alcohol, lauryl alcohol, ste'aryl alcohol, wax alcohols, and alcohols obtained by the oxidation of petroleum hydrocarbons. A group of alcohols of special interest are the Oxo alcohols, prepared by the reaction of carbon monoxide and hydrogen upon the olefins obtainable from petroleum products andv hydrogenation of the resulting aldehydes. Such alcohols usually have a branched chain structure. Other alcohols which may be employed include unsaturated alcohols, such as oleyl alcohol and sulfurized alcohols, such as sulfurized oleyl alcohol, as well as substituted alcohols containing halogens or nitro groups. Likewise, cyclic alcohols, such as cyclohexyl alcohols, may be employed. An additional class of alcohols includes alcohols containing ether groups, illustrated by such compounds as ethylene glycol mono-n-butyl ether, diethylene glycol mono-2- ethylhexyl ether, dipropyleneglycol monomethyl ether, and tripropyleneglycol monoisopropyl ether. Many of these ether alcohols formed by the reaction of ethylene oxide or propylene oxide with aliphatic alcohols are known in the industry as Dowanols, Carbitols or Cellosolves. Among the phenols and naphthols which may likewise be employed in preparing organo-substituted acids of phosphorus are the simple phenols as well as alkylated phenols and analogous naphthols and their derivatives and phenol sulfides formed by reacting phenols with sulfur halides. i

The acids of phosphorus which may be employed in preparing the reaction products of the present invention may be organic-substituted thicphosphorous acids, thiophosphoric acids, thiophosphonic acids, and thiophosphinic acids, but the thiophosphoric acids are preferred. These organo-substituted thiophosphorus and thiophosphoric acids may be readily prepared by methods known to the art. These include reacting alcohols, mercaptans, phenols, or thiophenols with sulfides of phosphorus, e. g., P285, P487, P283 and the like. The salts are readily prepared by reaction with metal hydroxides, ammonium hydroxides, amines and the like.

Specific dithiophosphoric acids, whose salts may be used in the above reaction, include methylethyldithiophosphoric acid, diisobutyldithiophosphoric acid, dicyclohexyldithiophosphoric acid, di(methylcyclohexyl)dithiophosphoric acid, di(di isobutylphenol) dithiophosphoric acid, didecyldithiophosphoric acid, and the like.

The di-organo thiocarbamyl halides used in the practice of the present invention are readily prepared by means 2,743,235 Patented Apr. 24, 1956 beof; thev type mentioned. heretofore in connection with the. dithiophosphate salts.

pounds include, dimethylthiocarbamyl chloride, methylisopropylthiocarbamyl chloride; diisopropyl. thiocarbamyl chloride, di-n-butylthiocarbamyl .chloride, di-n-dodecylthiocarbamyl chloride, dioctadecylthioearbamyl chloride,.

phenylethylthiocarbamyl chloride and the like.

It is to. be understood that notonly single compounds such asmetallic. salts. of single acids of. phosphorus and single thiocarbamyl halides may be employed in the preparation of the products, but mixtures of salts of mixed. acids of phosphorus, as well as mixtures of thiocarbamyl halidesmay beemployed. in the preparationthereof. The products of the reactions involving such mixturesv will necessarily be mixtures of various'products, but these mixed'products willfall' within the general scope of, the above definition.

For general antioxidant purposes, and particularly when the additives are to be employed in mineral lubricating oils, the. amount of additive, based on the total composition, will: generally range from about 0.02 to about 5% by weight, preferably about 0.1to 3% by weight. The preparation and testing of. additives of the present invention are illustrated by the examples to be described. in detail below, but such examples are not to be construed as limiting thescope of the invention in any manner.

Example l.-Diethylthiocarbamyl chloride-potassium di-.

isopropyl dithiophosphate reaction product A mixture of 18.1 g; (0.12 mol) of diethylthiocarbamyl chloride, 30.2 g. (0.12 mol) of potassium; di isopropyl dithiophosphate, and 300' ml. of'petroleum ether-was re fluxed (48 C.) with stirring for 8 hours, during which tirne-the'white reaction mixture turned light yellow. The

white crystalline precipitate of potassium chloride was removed by filtration, followed by evaporation of the petroleum: ether on-the steam bath. 39.0 g. of a clear yellow liquid was obtained which analyzed 8.6% P, 29.1% S, and 4.1% N.

Example lI.-'Diethylthiocarbamyl chloride-potassium di- (methylcyclohexyl) dithiophosphate reaction' product This preparation was carried. out asv described in Example I. using 18.1 g. (0.12 rnol)v of di-ethylthiocarbamyl chloride and 43.2 g. (0.12v mol) of potassium di(methylcyclohexyl) dithiophosphate. A clear yellow liquid was obtainedwhich analyzed 6.0% P, 21.0% S, and 2.6% N.

Example lII.--Di-n-butylthiocarbamyl chloride-potassium div(tert.0ctylphen0l) dithiophosphate reaction product This preparation was carried out as described in Example I using 24.8 g. (O.12.mol) of di-n-butylthiocarbamyl chloride and 65.3 g. (0.12 mol) of potassium di(tert.- octylphenol) dithiophosphate. A viscous yellow oil was obtained which analyzed 3.3% P, 8.6% S, and 2.0% N.

Example IV. Di-isobutylthiocarbamyl chloride-potassium diz'sopropyl dithiophosphate reaction product Blends. containing; 0.25%. each; oftthe. products of; EX-

Specific thiocarbamyl' com 4 measure the effectiveness of the products in inhibiting the corrosiveness of a. typical mineral. lubricatingoil toward the surfaces of copper-lead bearings. The test was conducted as follows: 500 cc. offthe oil was placed in a glass oxidation tube (13 inches long and 2% inches in diameter) fitted at the bottom with a inch air inlet tube perforated to facilitate air distribution. The oxidation tube was thenimrnersedinaheating bath. so. that the oil temperature was maintained at 325 F. during the test.

amples I throughIV in aparatfinictype minerallubricating oil..of SAE-.-20. grade; andasample of the..unb.lende.d base oil were submitted-to a laboratory test. 'designedvto Two quartersections;of.automotivebearingsof the-copperlead alloy of known weighthaving a total areznofls sq. cm. were attached to opposite sides of a stainless: steel rod which-was then immersedin the test oil and rotated at 600 R. P. M., thus.providingsufiicient agitation of the sample during the test. Air was then blown through the oil at a rate of 2 cu. ft: per'houn. Attheend of each fourhour. period the bearings were removed, washed with naphtha and weighed to determine the amount of loss by corrosion; Thebearings were. then repolished (toincreasethe severityof; the test), reweighed, and

jected to; the: test for additional four-hourrperiodst.inzlike manner: The; results. are given: in the=.fo1lowing;table:as:; corrosion; life, which indicates the number: on

required for the bearings to lose. mg. in:.weight-, determined by interpolation of;the.-da.ta obtained-in the various periods.

Additive in Bearing corrosion The p'roductsofjthe present invention may beemployed not only-in ordinary hydrocarbon lubricating oils: but' also in the heavy duty type of lubricating oils which have been compounded with such detergent type additivesas metal soaps,- metal petroleum: sulfonates; metal phenates, metal alcoholates, metal alkyl phenol'sulfides, metal organophosphates, thiophosphates, phosphites and thicphosphites, metal: salicylates, metal xanthates and thic xanthates, metal thiocarbarnates, amines and amine demaatives-,. reaction products. ofmetal phenates and sulfur,

reactionv products of metal phenates and. phosphorus suli fides, metal phenolsulfonates, and the.like.=. Thusthe additives ofthe. present. invention may be used in lubri-.--

cating oils :containi'ng-:suchotheradditionagentsasabarimrr; tert.-octylphenol sulfide, calcium.tert.-amylphenol sulfide,

nickel oleate, barium octadecylate, calcium phenyl stearate, zinc diisopropyl salicylate, aluminum naphthenate, calcium cetylphosphate, barium di-tert.-amylphenol sulfide, calcium petroleumsulfonate, zinc methylcyclohexyl' thiophosphate, calcium dichlorostearate, etc. Other types ofadditives, such as phenols and phenol sulfides,

may be employed.

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paratfinic, naphthenic. as-.

phaltic, 'or mixed base crudes, or, if desired, various,

blendedoils maybe employed as well as residuals, particularly those from which asphaltic constituents have" been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay ot" other agents such as aluminumchloride, or'-they"may be extracted oils produced, .for'example by: solvent extrac' tionwith solvents of-the type ofphenol; sulfur dioxide; furfural, dichlorodiethyl ether, nitrobenzene; crotonaldthyde; etc.- HydrogenatedoiIsor white oils may'be employed as well as synthetic oilsprepared; for example; by-

the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. fractions-,and coal. tar. or shale oil distillatesmay also be used. Also, .for special applications, animal, vegetable In certain instances cracking eoalitar' or fish oils or their hydrogenated or volatilized products may be employed in admixture with mineral oils.

For the best results the base stock chosen should normally be an oil which without the new additive present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils or other oil-s, no strict rule can be laid down for the choice of the base stock. Certain essentials must of course be observed. The oil must possess the viscosity and volatility characteristics known to be required for the service contemplated. The oil must be a satisfactory solvent for the additive, although in some cases auxiliary solvent agents may be used. The lubricating oils, however they may have been produced, may vary considerably in viscosity and other properties depending upon the particular use for which they are desired, but they usually range from about 40 to 150 seconds (Saybolt) viscosity at 210 F. For the lubrication of certain low and medium speed diesel engines the general practice has often been to use a lubricating oil base stock prepared from naphthenic or aromatic crudes and having a Saybolt viscosity at 210 F. of 45 to 90 seconds and a viscosity index of to 50. However, in certain types of diesel engine and gasoline engine service, oils of higher viscosity index are often preferred, for example, up to 75 to 100, or even higher, viscosity index.

In addition to the material to be added according to the present invention, other agents may also be used such as dyes, pour depressors, heat thickened fatty oils, sulfurizecl fatty oils, organo-metallic compounds, metallic or other soaps, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, volatilized Waxes and colloidal solids such as graphite or zinc oxide, etc. Solvents and assisting agents, such as esters, ketones, alcohols, aldehydes, halogenated or nitrated compounds, and the like may also be employed.

Assisting agents which are particularly desirable as plasticizers and defoamers are the higher alcohols having eight or more carbon atoms and preferably 12 to 20 carbon atoms, e. g., lauryl alcohol, stearyl alcohol, wax oxidation alcohols, and the like.

In addition to being employed in crankcase lubricants the additives of the present invention may also be used in extreme pressure lubricants, engine flushing oils, industrial oils, general machinery oils, process oils, rust preventive compositions and greases.

The additives of the present invention may be employed as antioxidants or stabilizing agents not'only in mineral lubricating oils, but also in petroleum hydrocarbon oil products, generally, where improved resistance to oxidation is desired. Thus the products may be added to motor oils, diesel fuels, kerosene, hydrocarbon polymer oils, and the like.

What is claimed is:

l. A mineral lubricating oil having incorporated therein an oxidation inhibiting amount of a compound having the formula wherein R is an aliphatic hydrocarbon radical, R1 is a hydrocarbon radical, and R and R1 each contain in the range of 1 to 15 carbon atoms.

2. A composition according to claim 1 in which R is an alkyl group having in the range of 1 to 15 carbon atoms.

3. A composition according to claim 2 in which R is an ethyl radical.

4. A composition according to claim 3 in which R1 is an isopropyl radical.

5. A composition according to claim 3 in which R1 is a methylcyclohexyl radical.

6. A composition according to claim 2 in which R is a butyl radical.

7. A composition according to claim 6 in which R1 is a tert.-octyl phenol radical.

8. A composition according to claim 6 in which R1 is an isopropyl radical.

References Cited in the file of this patent UNITED STATES PATENTS 2,494,283 Cassaday et a1. Jan. 10, 1950 2,506,049 Waitkins May 2, 1950 2,566,288 Hook et al Aug. 28, 1951 

1. A MINERAL LUBRICATING OIL HAVING INCORPORATED THEREIN AN OXIDATION INHIBITING AMOUNT OF A COMPOUND HAVING THE FORMULA 